Automatic pressure-retaining valve for air-brakes



. (No Model.)

T. P. SWEENEY. 7 AUTOMATIC PRESSURE RETAINING VALVE FOR AIR BRAKES.

No. 416,516. Patented 1300.3, 1889.

UNITED STATES PATENT I OFFICE.

THOMAS P. S'WEENEY, OF SACRAMENTO, CALIFORNIA.

AUTOMATIC PRESSURE-RETAINING VALVE FOR AIR-BRAKES SPECIFICATION formingpart of Letters Patent No. 416,516, dated December 3, 1889. Applicationfiled December 8. 1888- Serial No, 293,010. (No model.)

To all whom it may concern:

Be it known that I, THOMAS P. SWEENEY, of Sacramento, Sacramento county,State of California, have invented an Improvement in Automatic Pressure-Retaining Valves for Air-Brakes; and I hereby declare the following tobe a full, clear, and exact description of the same.

My invention relates to improvements in air-brakes; and it consists ofwhat I term an automatic pressure-retaining valve, which may be operatedin connection with the resfixed upon each car, having avalvemechanism,

which is called a triplevalve', through which air is admitted to thereservoir, and by which it is also admitted from the reservoir to thebrake-cylinder by the reductionof the pressure in the train-pipe butwhen it is necessary to replenish the auxiliary reservoir it isnecessary to temporarily out off the communication between thisreservoir and the brakecylinder, so that the latter is without pressurewhile the reservoir is being replenished, and

the movement of the valves to .connect the reservoir with the train-pipeallows the'air to escape from the cylinder. When this occurs upon heavydowngrades, it is a dangerous thing, because the train will gain suchmomentum in a very short distance that it will be almost impossible tohandle it and again check it. My invention is designed to overcome thisdifficulty; and it consists in the employment of what I term apressureretaining valve, which regulates or prevents the escape of airfrom the brake-cylinder while the train-reservoir is being replenished.

In the drawings, A is the train-pipe, through which the air passes inthe direction shown by the arrows.

B is a triple-valve mechanism, so called.

C is an auxiliary reservoir, and D is the brake-cylinder. These portionsof the apparatus being well shown in the patents already issued and inuse upon what is known as the Westinghouse system, I shall not furtherdescribe them in this place.

E is a supplemental cylinderin which is fitted a cylindrical valve F.This cylinder is placed in a vertical position and has an opening in itstop and also in its bottom. The opening in the bottom of the cylinder isconnected with the train-pipe A, so that the pressure from said pipe mayact upon the bottom of the piston-valve F to raise it, the interior ofthe cylinder being enough longer than the valve to allow it a certainamount of movement longitudinally within the cylinder. At the upper endof the supplemental cylinder is an extension forming a chamber E, Whichis connected by a pipe L with the auxiliary or car reservoir. Ahorizontal passage J is made transversely across the valve F, and holesare made in opposite sides of the cylinder E, which holes correspondwith the passage in the valve when the valve is at its lowest point; butwhen the valve is raised its passage will be carried above the line ofthe holesin the sides of the cylinder and will thus cut offcommunication through them.

T is the discharge passage or opening in the triple-valve chamber,through which air from the brake-cylinder is ordinarily allowed toescape by the movement of the triple valve, which allows the auxiliaryreservoir to be recharged. Above the upper end of the cylinder E is anextension, forming a chamber E,

having within it a piston N, which is'provided with a stem M, extendingdownward through the head or diaphragm which separates the chambers Eand E. This opening T, as ordinarily employed, allows the air to escapefrom the brake-cylinder D when the triple valve is so moved as to makeconnection between the train-pipe A and the auxiliary reservoir 0; butin the present case this escape-opening T is connected by a pipe atdirectly with the side of the valve-chamber E and the transverse passageJ through the valve F.

V is the pipe which connects the brakecylinder with the triple-valvechamber, and through which, when the valves are in proper position, airpasses from the reservoir 0 to the brakecylinder 1), so as to apply thebrake. In the ordinary construction, when the triple valve is moved soas to admit air from the train-pipe to the reservoir, it also allows airto escape from the brake-cylinder through the pipe V and the opening T.

The operation of the device will then beas follows: Air is pumped intothe reservoir upon the engine to a pressure, say, of one hundred pounds,and by means of the engineei"s valve it is allowed to pass through thetrain-pipeA into the auxiliary reservoirs C,which are beneath each car.The triple-valve mechanism, which is already in use, and is thereforenot here described, is so arranged that when the pressure from thetrain-pipe A is admitted into the triple-valve chamber 13 it moves thevalves so as to open communication directly with the reservoir 0, sothat air may flowinto this reservoir up to any desired pressure. Thismovement of the valve alsoopens comllllllllOittIOll between thebrake-ey1inderD and the opening '1, which is ordinarily anescapeor'discharge passage, but which in my inventioneommunicates through thepipe awith the side of the cylinder-E, as above described. Nowqwhen itis desired to applythe brake, suppose the pressure in the reservoirC tostand at seventy pounds. By means of the engineers valve the pressure inthe trainpipe'may bereduced to something less than the pressure in thereservoir. The triple valve will then be moved so as to opencommunication between the reservoir 0 and the brake-cylinder D, and anyrequired pressure may be admitted into the cylinder-D. "hen running downgrades the leakage and gradual escape of the air will reduce thepressure in the auxiliary reservoir 0 until it is below what isnecessary for the proper control of the train. It is then necessary toresupply the auxiliary reservoirs from the engine-reservoir by 'means ofthe engineers valve. Air is allowed to pass through the train-pipe A,and acting upon the valves in the chamber 13 communication is openedbetween the trainpipe and the reservoir C, and at the same timecommunication is opened between the brake-c'ylinderD and the dischargeopeni-ng '1. As formerly arranged the air would be allowed to escapefrom the brake-cylinder, and the train would be temporarily out ofcontrol of the brakes and would be liable to attain a dangerous speed.In my invention, however, the pressure in the train-pipe, aeting throughthe pipe G upon the bottom of thevalve F, forces this valve up until thepassage J in the valve is out of line with the pipe a and the openingsin the sides of the valve-chamber E. The pressure in the brakecylinderis thus retained, because this valvc' cuts off the escape of the airthrough the hole T. \Vhen the pressure in the reservoir C is such as tobalance the pressure in the trainpipe A, it acts through the pipe L,which connects the upper cylinder E with the reservoir G, and pressingupon the piston M forces it down, and through the stem M the valve F isalso'forced down until the passage J is in line with the pipe or, whenair maybe allowed to escape from the brake-cylinder D to any desireddegree. By reducing the pressure in the train-pipe to less than that inthe reservoir C the valves in the chamber B will again be moved so as toadmit air into the brakecylinder D. The amount of pressure in thetrain-pipe and this cylinder is controlled by the engineefis valve inthe wellknown manner.

Inorder to insure theprompt movement of the valve'or piston F as soon asthe pressures in the auxiliary reservoirand the train-pipe areequalized, I have shown a light spring I), so disposed in the upperpartof the valve chamber E as to pressupon the top of the valve F. g

I have shown the valve chamber E at some distance from themainvalve-chamber 13,1301 convenience in describing; butin practice it maybeplaced in close eonnectionwitlrthe discharge-opening T, so as tomake-the" whole compact.

The object of the device is to keep thcb 'akes applied while thetrain-reservoirs are being recharged without in any way disturbing thevalve mechanism atpresenirin useand by an exterior supplemental device.

I do not wish to limit myselfto thespecilic arrangement and constructionof parts herein shown, as thesame may be modified or changed withoutdeparting from'the spirit of myinvention.

Having thus described in y invention, what I claim as new, and desire tosecure bylietters Patent, is-

1. The improvement in automatic air-brake mechanism, consisting ofacutoff valve connected with the triple-valve mechanism and exteriorthereto, said valve acting to close the escape-passage from thebrake-cylinder by the increase of train-pipe pressure.

2. The combination, with the auxiliary reservoir, brake-cylinder, andintermediate triplevalve mechanism of an automatic air-brake, of acylindrical valve-chamber having openings made in its opposite sides inline with each other, a piston fitted to move within said cylinder andhaving a hole made transversely through it corresponding with the holesin the sides of the cylinder when said piston is at one end of itsstroke, a pipe connecting this end of: the cylinder with the trainair-supply pipe, a second'pipe connecting the opposite end "of thecylinder with the auxiliary reservoir, and a pipe connecting one of theopenings in the side of the valve-cylinder with the escape-passage atthe triple-valve chamber,

whereby said passage is closed by the upward movement of the pistonwithin the supplemental cylinder, substantially as described.

3. A supplemental cylindrical valve-chamher having openings in theopposite sides, a vertically-moving piston fitted therein and having atransverse opening corresponding with the openings in the sides of thechamber, in combination with the brake-cylinder, auxiliary reservoir,train-pipe, and triple-valve mechanism connected therewith, a pipeconnecting one 01": the openings in the side of the supplementalcylinder with the escape-passage of the triple-valve mechanism, a secondpipe connecting the bottom of said cylinder with the train-pipe, and apipe connecting the top of saidcylinder With the auxiliary reservoir,substantially as described.

4. The automatic air-brake mechanism, consisting of the auxiliaryreservoir, the brakecylinder, and the valves, whereby the supply anddischarge of air is effected, in combination with a supplementalcylinder, apiston reciprocating therein, pipes connecting the oppositeends of said cylinder with the train-pipe and auxiliary reservoir, apassage through said reciprocating piston, and corresponding openings inthe side of the cylinder, one of which is connected with theauxiliary-reservoir valve mechanism, so that the movements of thesupplemental piston in its cylinder will close or open the passage andsimultaneously close or open the discharge from the brakecylinder,substantially as dscribed. 5. The automatic air-brake mechanism,consisting of an auxiliary reservoir, the brakecylinder, and the triplevalve mechanism whereby the supply and discharge of air is effected, asupplemental cylinder having apiston reciprocating therein and theopposite ends of said cylinder connected with the trainpipe andauxiliary reservoir, a transverse opening through said piston, andcorresponding openings in the sides of the supplemental cylinder,together with a supplemental piston fitted in the upper part of thesupplemental cylinder, having a stem extending downward and pressingupon the top of the main piston, and a spring surrounding said stem andacting ,upon the main piston, substantially as described.

In Witness whereof I have hereunto set my hand.

THOMAS P. SWEENEY.

WVitnesses f S. H. NOURSE, H. 0. LEE.

